Effect of hydration on experimentally induced cerebral edema.

Although fluid restriction is often used to manage cerebral edema, there have been no controlled studies which demonstrate its benefit. We evaluated the effects of dehydration and overhydration on the development of cerebral edema in rats subjected to triethyltin poisoning or anoxic ischemia. Four days after triethyltin poisoning, the brains of control rats receiving maintenance hydration had a mean percentage of water of 79.56%; dehydration (5% of body weight) and overhydration groups were not statistically different at 79.95% and 79.86%, respectively. Forty-seven hours after an anoxic-ischemic insult consisting of unilateral carotid artery ligation and subsequent exposure to a 4% oxygen atmosphere for 30 min, the percentage of water in control rats was 79.12%; dehydration (13% of body weight) and overhydration groups were 79.10% and 79.16%, respectively. Histopathologic analysis of brain sections did not differentiate the hydration groups (triethyltin model only). Thus, cerebral edema was not altered by hydration status in either poisoned or ischemic animals.